The long term objective of this research is the production of surfaces which impede the apical migration of epithelium on dental implants. We have shown, using human gingival explants, that the epithelium migrating from the explant can be guided by a titanium-coated grooved surface produced by techniques used in the microelectronics industry. However, the grooved surface is not an absolute barrier and some cells were able to circumvent it. The mechanism proposed to explain contact guidance is that the cells are unlikely to band around edges because of the relative stiffness of their microfiliament bundles. This mechanism predicts that surfaces with grooves which force the cells to negotiate sharper angles would be even more effective in controlling the direction of cell migration. The first specific aim is to produce such surfaces and the first step is determining the spacing and geometry of grooves. These studies will use epithelial cells in vitro and the surfaces will be produced by the photolithograph/silicon mask/etch method. The second specific aim is the testing of the surfaces in vivo using rats as an animal model. Silicon surfaces will be produced with grooves of the dimensions and spacing found optimal in the first part of the study. Litanium-coated epon replicas of these surfaces will be inserted in rats with the grooves oriented either parallel or perpendicular to the long axis of the root. The rate of migration of attachment epithelium will be measured by standard morphometric techniques. The rate of proliferation will be determined by continuous infusion of the animals with tritiated thymidine delivered by an osmotic mini-pump followed by autoradiography. The attachment of the epithelium will be observed using transmission electron microscopy. The rat system should allow sufficient implants to be placed to allow meaningful statistical analysis. The end result of this study should allow the specification and production of surfaces which impede epithelial migration but allow normal proliferation and attachment. The results will be useful for the design of dental and trans-cutaneous implants, where epithelial migration has caused problems.